An active matrix substrate is widely used in an active matrix-type display device such as a liquid crystal display device and an EL (Electroluminescence) display device. For example, the main part of the active matrix-type liquid crystal display device is composed of a liquid crystal panel and drive circuits thereof, and the liquid crystal panel typically includes: the active matrix substrate having pixel circuits arranged in a matrix, each of which contains a thin film transistors (hereinafter, simply abbreviated as “TFT”) as a switching element and a pixel electrode and the like; an opposite substrate of a transparent insulating substrate such as a glass plate having an opposite electrode and an alignment film which are sequentially deposited over the entire surface thereof; a liquid crystal layer sandwiched between the both substrates; and polarizer plates attached to the outside surfaces of the both substrates, respectively.
FIG. 23 is a plan view showing a structure of a conventional active matrix substrate 700 used for the liquid crystal display device as described above, and illustrates a pattern configuration in a part corresponding to one pixel. The active matrix substrate 700 includes a plurality of data signal lines 715, a plurality of scanning signal lines 716 intersecting the plurality of data signal lines 715, TFTs 712 as the switching elements, which are formed in the neighborhoods of the intersections of the plurality of data signal lines 715 and the plurality of scanning signal lines 716, respectively, and pixel electrodes 717. The scanning signal line 716 works also as a gate electrode of the TFT 712, a source electrode 719 of the TFT 712 is connected to the data signal line 715, and a drain electrode 708 thereof is connected to the pixel electrode 717 via a drain extraction electrode 707. A hole is formed in an insulating film disposed between the drain extraction electrode 707 and the pixel electrode 717 and thereby a contact hole 710 is formed connecting the drain extraction electrode 707 and the pixel electrode 717. The pixel electrode 717 is a transparent electrode made of ITO (Indium Tin Oxide) or the like and transmits light from the back of a liquid crystal panel including the active matrix substrate 700 (light from a backlight).
In the active matrix substrate 700, the TFT 712 is turned on by a gate-on voltage of a scanning signal applied to the scanning signal line 716 (conductive state between the source electrode 719 and the drain electrode 708), a data signal applied to the data signal line 715 in this state is written into a pixel capacitance (capacitance formed by the pixel electrode 717 and the opposite electrode) via the source electrode 719, the drain electrode 708, and the drain extraction electrode 707. Note that, in this active matrix substrate 700, a storage capacitance line 718 is formed along the scanning signal line 716 and this storage capacitance line 718 has a function for avoiding self discharge of the liquid crystal layer during an OFF period in the TFT 712, and the like.
Meanwhile, in an impulse type display device such as a CRT (Cathode Ray Tube), when focusing on each pixel, an ON period when an image is displayed and an OFF period when an image is not displayed are repeated alternately. For example, when a moving image is displayed, the OFF period is inserted when an image of one screen is rewritten and a residual image of a moving object is not produced in human visual sense. Thereby, the object and the background thereof can be distinguished clearly and the moving image can be viewed without uncomfortable feeling.
On the other hand, in a hold type display device such as the liquid crystal display device using the active matrix substrate as described above, luminance of each pixel is determined by a voltage retained in its pixel capacitance, and the retained voltage in each of the pixel capacitances is maintained during one frame period, once rewritten. In such a hold type display device, the voltage to be retained in the pixel capacitance as pixel data is retained, once written, until the pixel capacitance is rewritten next, and thereby the image in each frame is temporally close to the image one frame prior thereto. This produces the residual image of the moving object in the human visual sense when the moving image is displayed. For example, as shown in FIG. 22, a residual image AI is produced as an image OI representing a moving object is dragging a tail (hereinafter, called “tail-dragging residual image”).
Since such a tail-dragging residual image is produced in the moving image display of the hold type display device such as the active matrix-type liquid crystal display device or the like, conventionally the impulse type display device has been employed typically for a display such as a television or the like which mainly displays the moving image. However, the display such as the television or the like recently has been required strongly to have a lighter weight and a slimmer body and the hold type display device such as the liquid crystal display device which is easily to have the lighter weight and the slimmer body has been employed rapidly for such a display.    Patent document 1: Japanese Patent Application Laid-Open No. H4-309995    Patent document 2: Japanese Patent Application Laid-Open No. H5-119346    Patent document 3: Japanese Patent Application Laid-Open No. 2003-255912    Patent document 4: Japanese Patent Application Laid-Open No. 2003-66918    Patent document 5: Japanese Patent Application Laid-Open No. H9-243998    Patent document 6: Japanese Patent Application Laid-Open No. 2004-61590